Locking system for a blowout preventer function

ABSTRACT

A hydraulic locking system for a blowout preventer function is provide. The locking system enables implementation and practical engagement as part of the routine functioning of the blowout preventer. The locking system may be adapted to fluidly interconnect a control system port and a function port so as to trap and release hydraulic actuation pressure against the function port and any blowout preventer function fluidly communicating thereto.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority of U.S. provisionalapplication No. 62/024,560, filed 15 Jul. 2014, the contents of whichare herein incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to blowout preventers and, moreparticularly, to a hydraulic locking system for a blowout preventerfunction, wherein the locking system enables implementation andpractical engagement as part of the routine functioning of the blowoutpreventer.

A blowout preventer is a large, specialized valve or similar mechanicaldevice, usually installed redundantly in stacks, used to seal, controland monitor oil and gas wells. Blowout preventers were developed to copewith extreme erratic pressures and uncontrolled flow emanating from awell reservoir during drilling that can lead to a potentiallycatastrophic event known as a blowout. The term BOP (pronounced B-O-P,not “bop”) is used in oilfield vernacular to refer to blowoutpreventers. As used herein, unless specified otherwise the terms“blowout preventer,” “BOP,” “blowout preventer function,” “blowoutpreventer stack,” “blowout preventer system,” “BOP stack” are to begiven their broadest possible meaning manner to describe an assembly ofseveral stacked blowout preventers of varying type and function, as wellas auxiliary components.

Practically all commonly available BOP hydraulic actuation systems usethe continuous application of hydraulic pressure to an actuated functionas the primary means of ensuring that the actuated BOP function issustained. As a result, if the pressure integrity of said BOP hydraulicactuation system is lost, the sustaining pressure of the actuated BOPfunction is also lost.

Currently, devices based on mechanical locking methods are used to lockBOP functions. Such devices are commonly based on manually actuatedscrews which take time to actuate and require direct access by personnelto the BOP stack. Moreover, such devices are normally impractical toengage mechanical BOP function locking systems as a routine precautionfor situations when and where hydraulic actuation pressure loss.

As can be seen, there is a need for a hydraulic locking system for ablowout preventer function, wherein the locking system enablesimplementation and practical engagement as part of the routinefunctioning.

SUMMARY OF THE INVENTION

In one aspect of the present invention, a system for locking actuationpressure in a BOP function includes a control system configured tocontrol a hydraulic pressure therein; a control line fluidlycommunicating the BOP function to the control system; and a hydrauliclocking apparatus disposed along the control line, wherein the hydrauliclocking apparatus having a function port adapted to fluidly communicateto a portion of the control line connected to the BOP function; acontrol system port adapted to fluidly communicate to a portion of thecontrol line connected to the control system; and a locking mechanismmovable from an unlocked configuration to a locked configuration,locking the actuation pressure against the function port.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdrawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an exemplary embodiment of the presentinvention;

FIG. 2 is detail view of an exemplary embodiment of the presentinvention; and

FIG. 3 is a detail view of an exemplary embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is of the best currently contemplatedmodes of carrying out exemplary embodiments of the invention. Thedescription is not to be taken in a limiting sense, but is made merelyfor the purpose of illustrating the general principles of the invention,since the scope of the invention is best defined by the appended claims.

Broadly, an embodiment of the present invention provides a hydrauliclocking system for a blowout preventer function, wherein the lockingsystem enables implementation and practical engagement as part of theroutine functioning of the blowout preventer. The locking system may beadapted to fluidly interconnect a control system port and a functionport so as to trap and release hydraulic actuation pressure against thefunction port and any blowout preventer function fluidly communicatingthereto.

Referring to FIGS. 1 through 3, the present invention may include ahydraulic locking system 20 for a blowout preventer function, whereinthe locking system enables implementation and practical engagement aspart of the routine functioning. The locking system 20 may embody aplurality of apparatuses and methods thereof for hydraulically lockingBOP functions.

Typically, a BOP includes a control system 3 fluidly communicating tothe BOP function by way of a control line 18, as illustrated in FIG. 1.The locking system 20 may be disposed along the control line 18 so as tofluidly interconnect the BOP function and the control line 18. Thelocking system 20 may include a function port 6 and a control systemport 7 fluidly communicating to the BOP function and a control system 3,respectively, as illustrated in FIG. 2. In certain embodiments, anaccumulator 5 may be connected in series to the portion of the controlline 18 interconnecting the BOP function and locking system 20. Forexample, the locking system 20 may be fluidly connected to the functionport 6.

The locking system 20 may include a check valve 1 and a two-way valve 2connected in parallel to the control line 18, as illustrated in FIG. 1.The check valve 1 may include a passage cavity fluidly communicating thefunction port 6 to the control system port 7, as illustrated in FIG. 2.In certain embodiments, a check-spring 12 may operably engage a ballcheck 8 dimensioned and adapted to operatively block an esophagus,preventing the passage of actuation and/or hydraulic fluid flowingtherethrough, whereby the resulting actuation pressure may be trappedagainst the function port 6. In certain embodiments, a bleed valve 14may be disposed in the passive cavity between the function port 6 andthe esophagus, wherein the bleed valve 14 may be adapted to allow apredetermined amount of actuation fluid and/or hydraulic pressure toflow therethrough. The check valve 1 may be adapted so that the ballcheck 8 may be urged away from the esophagus, allowing the flow ofactuation and/or hydraulic fluid. In certain embodiments, apneumatically operated stem 9 may be disposed in the check valve 1 forurging said ball check 9 (locking mechanism). The operated stem 9 may beadapted to be movable from an unlocked configuration to a lockedconfiguration, operatively hydraulically locking the actuation pressureagainst the function port 6. The unlocked configuration of this ballcheck and stem assembly may result from controlled pneumatic pressure bya pneumatic cylinder assembly 10 communicating to a pneumatic port 13,and the locked configuration is urged by a return spring 11, asillustrated in FIG. 2.

In an alternative embodiment, the check valve 1 locking mechanism mayinclude a poppet 15 for trapping the actuation pressure against thefunction port 6, wherein the poppet may be dimensioned and adapted tooperatively block the esophagus, as illustrated in FIG. 3. The poppet 15may be operatively urged by a long stem 16 biased by a poppet spring 17,whereby this poppet and stem assembly may be movable from the unlockedconfiguration to the locked configuration, operatively hydraulicallylocking the actuation pressure against the function port 6.

A method of using the present invention may include the following. Thehydraulic locking system 20 disclosed above may be provided. Thehydraulic locking system 20 may be adapted to allow pressurizedactuation fluid to flow to the BOP function being activated. Once apredetermined maximum actuation pressure delivered through the controlline 18 is realized, the hydraulic locking system 20 may be adapted totrap actuation fluid within the function port 6 so as to hold andsustain the activated BOP function. Optionally, the hydraulic lockingsystem 20 may trap actuation pressure in the accumulator 5.Alternatively, if the hydraulic locking system 20 may be adapted toequalize actuation pressure across the control system and function ports7, 6, respectively. The hydraulic locking system 20 may be adapted toallow fluid to flow from the activated BOP function when it isdeactivated.

When the BOP function is activated, the check valve 1 may be eitheropened or already opened so that hydraulic actuation pressure and flowmay be allowed to pass through the check valve 1 to actuate the BOPfunction 4. Once the actuation pressure from the control system 3through the check valve 1 remains constant or begins to decline, thehydraulic locking system 20 may be closed to trap actuation pressureagainst the function port 6. If the pressure on the control system1/control system port 7 of the valve ever exceeds the trapped pressureat or near the function port 6, the check valve 1 may be opened (theball check 8 and/or poppet 15 is urged from the esophagus) and pressureon the BOP function may be equalized to the higher control systempressure and then closed again.

By opening the hydraulic locking system 20 only when it is possible toincrease the pressure at or near the function port 6, a loss in BOPcontrol system pressure would not result in a loss of actuation pressureon the BOP function, as is the case for a vast majority of BOP controlsystems in use today.

In an alternative embodiment, the hydraulic locking system 20 couldfurther be enhanced by connecting the accumulator 5 to the control line5 on the BOP function portion of the locking system 20. The accumulator5 may be adapted to store actuation pressure to help sustain actuationpressure on the BOP function even if leaks were present in the controllines 18 and/or BOP function hydraulic seals.

Prior to deactivating the hydraulically locked BOP function, thepressure across the hydraulic locking system 20 would preferably beequalized to reduce valve wear, and then the hydraulic locking system 20could opened. The pressure in the actuated BOP function could then bevented through the control line 18 by the BOP control system 3, allowingthe opposing BOP function to be actuated.

The present invention may be manually or computer implements based inpart on predetermined actuation pressures.

Initially the opposing BOP function may be actuated and there is littleor no pressure in control system port 7 and the function port 6. In thisinitial depressurized condition the two-way valve 2 may be in the closeposition. If the BOP control system 3 vents the actuation pressure onthe opposing BOP function and pressurizes BOP control system port 7,fluid pressure is free to automatically by-pass the closed two-way valve2 by flowing through the check-valve 1 and into the function port 6 toactuate the BOP function. If the accumulator 5 is installed, it maybegin filling once its pre-charge pressure is exceeded in the functionport 6. At this point the BOP function connected to the function port 6is fully actuated and pressurized. If by some unintended cause thepressure drops or is vented from the control system port 7, thecheck-valve 1 may automatically close and trap actuation pressure in thefunction port 6 (along with accumulator pressure if present) therebyhydraulically locking the actuated BOP function connected to thefunction port 6.

It is possible for the locking pressure trapped in the function port 6to drop in the event of leakage, for example through the bleed valve 14.If this occurs slowly enough, and hydraulic pressure may be restored tothe control system port 7 quickly enough, the check-valve 1 may open andre-pressurize the BOP function via pressure through the function port 6.Installation of the accumulator 5 may allow a higher actuation pressureto be sustained for a longer periods of time for a given leak rate.

In order to actuate the opposing BOP function, it would be preferable,but not necessary, to ensure that the control system port 7 may be firstpressurized to a predetermined full BOP control system pressure. Thisensures that the control system port 7 may be pressurized to apredetermined pressure higher than or equal to the pressure trapped inthe function port 6 and thereby would equalize the pressure across thetwo-way valve 2 through the check-valve 1. Equalizing the pressureacross the two-way valve 2 may reduce erosion and wear on the two-wayvalve 2 when it is subsequently opened in preparation for venting thepressure from the function port 6 and the attached BOP function.

It should be understood, of course, that the foregoing relates toexemplary embodiments of the invention and that modifications may bemade without departing from the spirit and scope of the invention as setforth in the following claims.

What is claimed is:
 1. A system for locking actuation pressure in a BOPfunction, comprising: a control system configured to control a hydraulicpressure therein; a control line fluidly communicating the BOP functionto the control system; and a hydraulic locking apparatus disposed alongthe control line, wherein the hydraulic locking apparatus comprises: afunction port adapted to fluidly communicate to a portion of the controlline connected to the BOP function; a control system port adapted tofluidly communicate to a portion of the control line connected to thecontrol system; and a locking mechanism movable from an unlockedconfiguration to a locked configuration, locking the actuation pressureagainst the function port.
 2. The system of claim 1, further comprisingan actuation fluid flowing through the control system under saidhydraulic pressure.
 3. The system of claim 1, wherein the hydrauliclocking apparatus further comprises a check valve.
 4. The system ofclaim 3, wherein the check valve further comprises a ball check and stemassembly.
 5. The system of claim 3, wherein the check valve furthercomprises a poppet and stem assembly.
 6. The system of claim 1, furthercomprising an accumulator fluidly interconnecting the locking mechanismand the function port.
 7. The system of claim 3, further comprising atwo-way valve connected in parallel with the check valve.
 8. The systemof claim 2, wherein the control system is configured to operatively movethe locking mechanism to the locked configuration at a predeterminedmaximum actuation pressure.
 9. The system of claim 8, wherein thecontrol system is configured to operatively move the locking mechanismto the unlocked configuration if the hydraulic pressure at the controlsystem port exceeds the hydraulic pressure at the function port.
 10. Thesystem of claim 6, wherein the accumulator is configured to storeactuation pressure to help sustain actuation pressure when the lockingmechanism is in the locked configuration.